Nitrofurantoin
Also known as: Macrobid, Macrodantin
What it's for
Nitrofurantoin is an antibiotic for urinary tract infections (UTIs). It concentrates in your urine to kill bacteria in your bladder and urinary tract.
Comes as: Capsules or liquid
How to take it
- Adults: Usually 50mg to 100mg, 4 times a day for 3 to 7 days.
- Or 100mg modified-release twice a day.
- Take with food or milk to reduce stomach upset.
- Drink plenty of fluids.
Doses here are typical. Always follow the instructions from your prescriber or on the packet — they come first.
Common side effects
- Feeling sick or loss of appetite
- Diarrhoea
- Headache
- Your urine may turn dark yellow or brown (this is harmless)
The leaflet inside the packet lists all known side effects.
Important safety points
- Not suitable if you have severe kidney problems
- Avoid in late pregnancy (last month)
- Can rarely cause lung problems with long-term use
- Tell your doctor if you have diabetes or vitamin B deficiency
Get medical help urgently if…
- You have difficulty breathing or a persistent cough
- You have tingling or numbness in your hands or feet
- You have yellowing of your skin or eyes
- You have severe stomach pain
Call NHS 111 for urgent advice, or 999 if someone is seriously unwell.
Before you act on anything here
This page is general information, written to help you understand — it is not personal medical advice and it cannot tell you what is right for you. Talk to your own GP, pharmacist or nurse about your own health.
- Need help now but it's not an emergency? Call NHS 111 or use 111.nhs.uk.
- Emergency? Call 999 or go to A&E.